While many investigators have identified possible impediments to improving glycemic control among patients with insulin-dependent diabetes mellitus (IDDM), this ongoing research has not yet led to improved psychosocial interventions. Thus, further research is needed to examine factors which may influence glycemic control. In a second project, we found that perceptions about what constitutes a comfortable glucose level discriminates patients extend our understanding of these initial observations about perceptions of symptoms, extend our understanding of these initial observations about perceptions of symptoms, moods, and glycemic control. Sixty adult (ages 18-45) patients with IDDM, but without known clinical complications will be studied. On the basis of their glycemic control over a two-year period, patients will be assigned to one of two contrast groups: poor glycemic control (HbA1 > 12%); and good control (HbA1 < 10%). To be eligible, patients must have insulin-dependent diabetes for 5-10 years. Patients will be studied under experimental conditions and also using relevant psychosocial measures. The insulin clamp technique will be used to systematically alter glucose level in order to assess patient experiences of glycemia-related moods and physical symptoms, and neuropsychologic functions under laboratory conditions. These contrast groups will also be compared in terms of field reports of glucose-related symptoms and moods. Other psychological assessments include: the personality variable of Repressive Style, using the Weinberger Adjustment Inventory; psychiatric symptoms and diagnosis, using the Symptom Checklist-90R and the Diagnostic Interview Schedule; the Hypoglycemia Fear Survey; the Diabetes Information Test; and the Diabetes Health Beliefs Evaluation. Our primary analyses will examine between groups differences in glycemia-related symptoms and moods and neuropsychologic functions from laboratory study. We will also examine relationships among the variables and use laboratory and psychosocial variables to develop a model which best discriminates poor and good control groups.